The literature that tests for U-shaped relationships using panel data, such as those between pollution and income or inequality and growth, reports widely divergent (parametric and non-parametric) empirical findings. We explain why lack of identification lies at the root of these differences. To...

This paper casts doubt on empirical results based on panel estimations of an "inverted-U" relationship between per capita GDP and pollution. Using a new data set for OECD countries on carbon dioxide emissions for the period 1960-1997, we find that the crucial assumption of homogeneity across...

The European Union (EU) advocates a plastic waste recycling rate of more than 55% through home separation by households. Even for the Netherlands, which has already invested heavily in plastic recycling policies, there is still a challenge to meet this target. We show that post separation is an...

The literature that tests for U-shaped relationships using panel data, such as those between pollution and income or inequality and growth, reports widely divergent (parametric and non-parametric) empirical findings. We explain why lack of identification lies at the root of these differences. To...